Break-through amplified spontaneous emission with ultra-low threshold in perovskite via synergetic moisture and BHT dual strategies
Dingke Zhang, Rui Li, Haoyue Luo, Zhen Meng, Jingwen Yao, Hongfang Liu, Yexiong Huang, Shuaiqi Li, Peng Yu, Jie Yang, Mingyu Pi, Shencheng Fu, Zhenxiang Cheng, Yichun Liu
Abstract
Micro-nano lasers hold significant promise for on-chip integrated photonics, where perovskite materials emerge as compelling gain media despite stability challenges. While moisture typically degrades perovskite structures, its controlled integration can paradoxically enhance crystallization. Here, we demonstrate a synergistic strategy utilizing water molecules and butylated hydroxytoluene (BHT) additive to achieve high-quality methylammonium lead iodide (MAPbI₃) films with low defect density. Through optimized BHT (4 wt%) combined with 95% relative humidity treatment, we attain an unprecedented amplified spontaneous emission (ASE) threshold of 8.987 μJ cm⁻² under nanosecond pulse excitation - the lowest value reported to date. This dual-triggered film completes ASE intensity retention after 30-day ambient storage. In situ structural and optoelectronic characterization reveals that BHT extends water-perovskite interaction, facilitating organic cation vertical diffusion and preferential (110)-oriented crystallization with 53.02% perpendicular alignment. Transient absorption (TA) spectroscopy confirms suppressed non-radiative recombination, evidenced by 11% prolonged carrier lifetime (6145 ps), while temperature-dependent photoluminescence reveals enhanced exciton binding energy (73.50 meV vs. 60.68 meV) conducive to low-threshold lasing. This work transforms moisture from a degradation agent into a crystallization promoter, establishing a paradigm for high-performance perovskite lasers with simultaneous efficiency and stability.